This invention relates to an electrophotographic printing machine, and more particularly concerns an improved stapling apparatus for use therein.
In the process of electrophotographic printing, a photoconductive member is charged to a substantially uniform level to sensitize the surface thereof. Thereafter, the charged photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive surface discharges the charge selectively in the irradiated areas. This records an electrostatic latent image on the photoconductive surface corresponding to the informational areas contained within the original document being reproduced. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer mix into contact therewith. The developer mix is brought into contact with the latent image, the greater attractive force thereof causes the toner particles to be attracted from the carrier granules of the developer mix to the latent image. Thereafter, the toner powder image is transferred to the copy sheet and permanently affixed thereto. This general approach was originally disclosed by Carlson in U.S. Pat. No. 2,297,691 and has been further amplified and described by many related patents in the art.
Frequently, it is desirable to reproduce a set of original documents as a plurality of sets of copies. This is generally achieved by employing a recirculating document handling system in association with the electrophotographic printing machine. The recirculating document handling system is positioned on the platen of the printing machine and advances successive original documents thereto. The original documents disposed on the platen are exposed and, subsequently reproduced. After being copied, each original document is returned to the stack of original documents so that it may be re-imaged for the next successive copying cycle. In this manner, collated sets of copies or booklets may be formed. Each set of copies corresponds to the set of original documents. The copy sheets of a specific booklet are stapled to one another. In high speed electrophotographic printing machines, it is highly desirable to utilize a stapling apparatus that possesses a storage compartment for extra staples. This minimizes the frequency of staple loading and reduces machine maintenance. Heretofore, it was necessary to shut the machine down after the staples in the stapling apparatus were depleted. However, with the utilization of a magazine storing an extra supply of staples, the down time of the printing machine is significantly reduced. In order to employ a magazine for automatically injecting new staples into the stapling head, it is advantageous to fix the stapler head. Previously, the stapling head pivoted during the stapling operation.
Accordingly, it is the primary object of the present invention to improve the stapling apparatus employed in an electrophotographic printing machine.